OLED lighting device

ABSTRACT

The invention relates to a lighting device ( 10 ) adapted to fit into a corresponding socket ( 1 ). The lighting device ( 10 ) has a base or housing ( 12 ) that at least partially embeds an OLED ( 11 ) and an electronic circuit ( 13   a,    13   b ) which affects the flow of electrical power from an external terminal ( 15   a,    15   b ) to the OLED. The electronic circuit may comprise a memory module, a communication module, a sensor etc. for allowing an intelligent control of the OLED and for making the lighting device ( 10 ) adaptable to possible changes in driving standards.

The invention relates to a lighting device that is adapted to fit into acorresponding socket and that comprises an organic light emitting diode(OLED) in a housing.

From the US 2006 198 128 A1 a method is known by which an LED togetherwith some hardware can completely be embedded into a transparentplastic. The resulting lighting devices are for special purposes onlyand not suited as low-cost devices.

Based on this background it was an object of the present invention toprovide an alternative lighting device, wherein it is desirable thatthis device is suited for mass production, a long-term use instandardized environments, and/or backward-compatible to olderstandards.

This object is achieved by a lighting device according to claim 1.Preferred embodiments are disclosed in the dependent claims.

A lighting device according to the present invention is adapted to fitinto a corresponding (standardized) socket and comprises the followingcomponents:

-   -   a) An organic light emitting diode, as usual abbreviated OLED in        the following. OLEDs have the advantage that they can be        operated at low voltage, have long operational lifetime, and can        be produced at low costs with large areas and in many colors.        For detailed information on OLEDs, reference is made to        literature (e.g. Joseph Shinar (ed.): “Organic Light Emitting        Devices, A survey”, Springer, 2004).    -   b) A housing that at least partially embeds the OLED. The        housing may for example be made from plastic, particularly by        injection moulding.    -   c) At least one external electrical terminal on the outer        surface of the housing via which electrical power can be        supplied to the lighting device. The arrangement and the        dimension of the external terminal preferably comply with some        standard, thus allowing to insert the lighting device into        compatible sockets from different manufacturers.    -   d) An electronic circuit disposed in the housing and comprising        passive and/or active electronic components (e.g. resistors,        capacitors, inductances, diodes, transistors etc.) that affect        the flow of electrical power from the external terminal to the        OLED.

The described lighting device has the advantage to combine in onehousing OLEDs and some more or less sophisticated electronic hardwarethat is concerned with the electrical control of the OLED. Thus there issome intelligence incorporated into the lighting device which can beexploited to achieve a more versatile control of the OLED, to implementsecurity mechanisms, and to make the device adaptive to possible futurechanges in the technology and the driving methods of OLEDs. Moreover,the lighting device with its housing (base) can be madebackward-compatible such that it can be exchanged in an existing socketand that the electronic components safeguard the performance of thedevice according to the specification of said socket, even though theOLED itself might have changed considerably.

The components of the lighting device, particularly the OLED and thehousing, are preferably connected to form a unitary structure, i.e. aproduct which can be handled as a single unit and for instance becompletely changed in case of a failure. Preferably, the OLED and thehousing are connected by material bonding, i.e. on the level ofatomic/molecular adhesion, for example via a glue that attaches them toeach other and seals them against dust or humidity.

The electronic circuit can be implemented in many different ways andfulfill various tasks. In one particular embodiment, the electroniccircuit comprises a programmable memory module for storing informationthat identifies the device and/or that affects the behavior of thecircuit. The fact that the memory module is “programmable” means thatthe information stored in it can be set or changed by electroniccommunication. The information can be stored in the memory by themanufacturer and remain unchanged during the whole lifetime of thelighting device (e.g. if the memory module is realized as a ROM orPROM). Preferably, the information module can however be changed ifnecessary at any time during the usage of the lighting device. Thisallows for example to dynamically allocate a unique address to thelighting device in case it is used in networks with varying composition.Moreover, it will be possible in this way to adapt the control of theOLED to the current standards of the external drivers, which are likelyto change in future due to ongoing rapid developments in the field ofOLEDs. Thus it will be possible to make the lighting device backwardcompatible (with older drivers) as well as forward compatible (with newdrivers not yet available at the time the lighting device was produced).Updating of the memory module could for example be achieved by reading abarcode from a new device and writing associated information (e.g.driver parameters) into the memory.

According to another embodiment, the electronic circuit comprises aswitching module for changing the routing or connection of the externalterminal in case of a failure. A short circuit is for example a typicalfailure of OLEDs; to prevent that other lighting devices used in thesame network are affected by such a short, the switching module can forinstance switch off and bypass the defect OLED in such a case.

The electronic circuit may optionally comprise a communication modulefor a uni- or bidirectional communication with external devices. Saidmodule may for instance comprise a receiver and/or a transmitter for awireless communication. Alternatively or additionally, it may be coupledto an external terminal (e.g. the same terminal via which power issupplied) for a communication by wire. Thus a communication with theelectronic circuit can be established which allows for example to readout operating parameters, sensory data, an address etc. and/or to makechanges in the electronic circuit from the outside.

According to yet another embodiment, the electronic circuit comprises aconverter module for converting a voltage applied to the externalterminal into a current which actually drives the OLED. Thus there is atransformation step between the external signal (voltage) and theinternal effect (current), which can optionally be adapted in case ofchanges in the standard of external drivers.

Furthermore, the electronic circuit may be equipped with one or moresensors, for example sensors for light, temperature, sound and/or theproximity of an object like a person. The sensor(s) may be used tosurvey the state of the lighting device, e.g. its operating temperature,wherein said sensory information can for example be communicated to someexternal higher level controller.

Preferably, the aforementioned sensor(s) is/are used to provide a signalthat (directly) affects the behavior of the electronic circuit. A lightsensor may for example be used to adjust the brightness or color of theOLED to the ambient illumination, or a temperature sensor may be used toreduce the power consumption of the OLED in case of a threateningoverheating.

The electronic circuit may particularly comprise a control module forcontrolling the brightness and/or the color of the OLED. As explainedabove, the activity of the control module may be subject to differentinfluences, for example the signals of sensors, the contents of amemory, or information communicated to the lighting device from outside.

To keep the size of the lighting device as small as possible andcompliant with a given standard, the electronic circuit is preferablydisposed in some recess which is provided in the housing.

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiment(s) described hereinafter.These embodiments will be described by way of example with the help ofthe accompanying drawings in which:

FIG. 1 shows schematically a section through a first embodiment of alighting device according to the present invention with electroniccomponents integrated into the housing;

FIG. 2 shows schematically a section through a second embodiment of alighting device according to the present invention with electroniccomponents arranged on a printed circuit board or foil;

FIG. 3 shows schematically an electronic circuit used in the lightingdevice according to the present invention.

Like reference numbers or numbers differing by integer multiples of 10refer in the Figures to identical or similar components.

It is highly probable that OLED technology will continue to changerapidly for many years. This leads to the problem that many standardsfor socket and base of lighting devices comprising OLEDs will follow ina short period. However, the lighting devices should be serviceable formany years.

Moreover, known OLEDs have a low efficiency, but this is expected toimprove dramatically in near future. This implies that drivers definedat the moment will not be compatible with OLEDs produced in a few years.Thus there is the problem that current solutions will probable not beserviceable in a few years.

Another problem is that the typical failure behavior of an OLED is theshort circuit. A common way of working is to connect a few OLEDs to asingle driver. If the OLEDs are connected in a parallel scheme, then ashort in one OLED will also prevent the others from lighting.

Since OLEDs will enable new applications, it is further likely thatthere will be a strong link between OLEDs and dynamic or interactivesolutions.

To address the above issues, it is proposed to provide some intelligencenear the lamp, i.e. in its base. This can make the OLEDs backwardscompatible and/or shut the OLED off in case of a short. Extending thebase with sensors, RF receivers or any other kind of communicationelectronics can furthermore create dynamic and interactive applications.Thus adding intelligence in the base will solve many problems and evenextend the application fields of the OLEDs.

FIG. 1 shows schematically a lighting device 10 according to a firstembodiment of the invention that realizes the aforementioned principles.The lighting device 10 comprises three main components:

-   -   An OLED 11 which typically comprises two glass plates with a        luminescent organic material in between.    -   A housing 12 or base which embeds the lower part of the OLED 11.    -   Electronic circuits 13 a, 13 b that are electrically integrated        in the electrical path from external terminals 15 a, 15 b to the        OLED 11.

The lighting device 10 is adapted to fit to a corresponding socket 1with electrical terminals for providing power, which is schematicallyindicated in the Figure. The housing 12 of this socket-base solutionprotects the OLED 11. It can favorably be made out of plastic. Moreover,a two-component plastic housing can be created where one component canbe used for wet plating of conductive tracks (and the other componentnot). Thus one can integrate conductive tracks 14 into the housing. Dueto the capabilities of the moulding process for the housing, there is a3D freedom; thus it is possible to integrate the electronic components13 a, 13 b in recesses of the housing, which keeps the small form factorof the OLED intact. The conductive tracks 14 allow to add any kind ofelectrical component into the housing. The OLED 11 can be connected tothese conductive tracks by means of welding, soldering, gluing or anyother connection method. After assembling the OLED 11 and the housing12, a filler-glue can be used to fill up air gaps and create amechanical stable construction.

The housing 12 can contain all sorts of electrical components in thecircuits 13 a, 13 b. This can be used for inrush-current limiting,circuit braking, efficiency adoption, sensors, dynamics, receivers, datacommunication, etc.

FIG. 2 shows an alternative embodiment of a lighting device 20. In thiscase, the base can be created in a more conventional way by combining aplastic or metal housing 22 with a separate printed circuit board (PCB)or foil 23, which is connected to the OLED 21 by lines 24 and furtherconnected to an external terminal 25.

By selecting a suitable plastic, the housings 12, 22 can also serve as aheat sink. This helps to reduce thermal problems of the OLED.

FIG. 3 shows schematically the components that the electronic circuit 13a (or any other circuit 13 b, 23) described above may contain. Thecircuit 13 a is shown to be electrically inserted into the line betweenthe external terminal 15 a and the OLED 11. In practice, the externalcircuit may further be connected to other internal or externalterminals, to additional electrodes of the OLED, or to any otherelectronic component of interest. The electronic circuit 13 a comprisesthe following (optional) components:

-   -   A memory 13.1 for storing information like an address of the        lighting device or operational parameters. The memory may        particularly be realized by a programmable read-only memory        (PROM, EPROM etc).    -   A switching module 13.2 by which for example the connection        between the external terminal 15 a and the OLED 11 can be        interrupted. Such an interruption may particularly take place if        some failure is detected, e.g. a short within the OLED 11 or        somewhere else.    -   A communication module 13.3 which allows a uni- or bidirectional        communication with external devices. The communication module        13.3 is shown to be connected to the external terminal 15 a to        realize a communication by wire. Alternatively, the        communication module might be connected to a terminal of its own        and/or comprise a receiver or transmitter for a wireless        communication by RF-signals.    -   A current converter 13.4 which converts an externally applied        voltage into a current needed to drive the OLED 11. The        characteristic of this converter may optionally be dependent on        the contents of the memory 13.1 or may in some other way be        changeable.    -   A sensor 13.5, for example a photodiode that measures the        ambient light and allows to adapt the brightness and/or color of        the OLED 11 accordingly.    -   A control module 13.6 connected to the aforementioned modules        13.1 to 13.5 and adapted to synchronize and control their        overall behavior. The control module may for example be realized        by a microcontroller.

In summary, the invention relates to a lighting device 10, 20 with ahousing 12, 22 that at least partially embeds an OLED 11, 21 and anelectronic circuit 13 a, 13 b, 23 which affects the flow of electricalpower from an external terminal 15 a, 15 b, 25 to the OLED. Theelectronic circuit may comprise a memory module, a communication module,a sensor etc. for allowing an intelligent control of the OLED and formaking the lighting device adaptable to possible changes in drivingstandards.

Finally it is pointed out that in the present application the term“comprising” does not exclude other elements or steps, that “a” or “an”does not exclude a plurality, and that a single processor or other unitmay fulfill the functions of several means. The invention resides ineach and every novel characteristic feature and each and everycombination of characteristic features. Moreover, reference signs in theclaims shall not be construed as limiting their scope.

1. A lighting device adapted to fit into a corresponding socket, thedevice comprising an OLED; a housing that at least partially embeds theOLED; at least one external terminal on the surface of the housing; anelectronic circuit disposed in the housing and comprising passive and/oractive electronic components that affect the flow of power from theexternal terminal to the OLED, and a programmable memory module forstoring information that identifies the device and/or that affects thebehavior of the circuit.
 2. The lighting device according to claim 1,wherein the OLED and the housing are connected to form a unitarystructure.
 3. The lighting device according to claim 1, wherein theelectronic circuit comprises a switching module for changing the routingof the external terminal in case of a failure.
 4. The lighting deviceaccording to claim 1, wherein the electronic circuit comprises acommunication module for a uni- or bi-directional communication withexternal devices.
 5. The lighting device according to claim 1, whereinthe electronic circuit further comprises a converter module forconverting a voltage applied to the external terminal into a current. 6.The lighting device according to claim 1, wherein the electronic circuitfurther comprises a sensor for detecting light, temperature, soundand/or proximity of an object.
 7. The lighting device according to claim6, wherein the behavior of the electronic circuit is affected by thesignal of the sensor.
 8. The lighting device according to claim 1,wherein the electronic circuit further comprises a control module forcontrolling the brightness and/or the color of the OLED.
 9. The lightingdevice according to claim 1, wherein the electronic circuit is disposedin a recess of the housing.
 10. A lighting device adapted to fit into acorresponding socket, the device comprising: an OLED; a housing that atleast partially embeds the OLED; at least one external terminal on thesurface of the housing; and an electronic circuit disposed in thehousing and comprising passive and/or active electronic components thataffect the flow of power from the external terminal to the OLED, and aswitching module for changing the routing of the external terminal incase of a failure.